She burst into tears as Judge Marsha Revel handed her the punishment for violating her probation for a driving under the influence arrest in 2007.
The 24-year-old star - who has been wearing an alcohol-monitoring SCRAM bracelet since May - told the Los Angeles court: "I did do everything I was told to do and did the best I could to balance jobs and showing up.
"I was taking it seriously. I wasn’t expecting any special treatment. I’m not taking this as a joke. It’s my life and my career, something I have worked for my entire life."
However, Judge Revel didn’t accept her plea and told her: "I couldn’t have been more clear about my orders. There are no excuses."
Lindsay was ordered to surrender on July 20 to begin serving the term and the judge also said she would be required to enter an in-patient rehabilitation programme after her release from prison.
In 2007, the ’Mean Girls’ actress pleaded guilty to two counts of being under the influence of cocaine and no contest to two counts of drunk driving and one count of reckless driving.
She went to jail but spent only 84 minutes behind bars and was also ordered to complete a series of alcohol education courses.
However, she failed to finish them on time and missed a number of meetings.
In May she was made to wear the SCRAM bracelet because she failed to attend a probation hearing, claiming she was stranded in France because her passport had been stolen.